The present invention relates generally to the field of surgical biopsy instruments and methods. More specifically, it relates to devices and methods for electrosurgically accessing a pathologically suspect tissue mass within a patient""s body, anchoring the device relative to the suspect tissue, and cutting tissue so as to isolate the suspect tissue and to facilitate the taking of a biopsy sample of the tissue mass, as well as to facilitate subsequent surgical procedures in the region of the tissue mass.
In diagnosing and treating certain medical conditions, such as potentially cancerous tumors, it may be desirable to perform a biopsy, in which a specimen of the suspicious tissue is removed for pathological examination and analysis. In many instances, the suspicious tissue is located at a subcutaneous site, such as inside a human breast. To minimize surgical intrusion into a patient""s body, it is desirable to be able to insert a small instrument into the body to gain access to the desired location for inspection and for extraction of a biopsy specimen.
Body tissue is often deformable, so that insertion of a needle or other device into a patient""s tissues will often deform or displace the tissue through which the needle or other device moves. Tissues of interest, such as nodules, masses, tumors and the like, which are typically the desired targets of a biopsy sample, may be readily displaced, pushed aside or otherwise deformed during biopsy procedures, making it likely that some or all of the desired target tissue may be missed during the biopsy procedure, thereby increasing the likelihood of misdiagnosis of the condition that led to the need for the biopsy.
In extraction of a biopsy specimen with a probe, it may be desirable to anchor the probe in a desired position so as to insure th at the probe remains in a proper position relative to the suspect tissue during manipulations and activities before and during the actual acquisition of the biopsy sample. In addition, it may be desirable to isolate tissue from neighboring healthy tissue in order to ensure that no diseased or abnormal tissue remains outside the sampled volume. Thus, the volume of tissue isolated may be larger than the minimum necessary so as to obtain margins of tissue free of disease for pathological diagnosis.
Electrosurgical techniques have been used in a variety of circumstances, including certain types of biopsy procedures. In electrosurgery, high frequency electrical energy is applied through a primary electrode to patient tissue. The electrical energy flows through the tissue to a return electrode that is in contact with the patent""s tissue. Typically, the return electrode is attached to the patient at a point remote from where the primary electrode contacts the tissue. The tissue adjacent the primary electrode is ablated, to form an opening in the tissue.
When electrically activated, the electrode ablates the tissue adjacent the electrode, to produce a tissue opening which provides access to tissue to be taken in a biopsy sample. Guidance of the electrode tip to the desired site within a patient""s body may be through stereotactic, radiological, ultrasonic, magnetic resonance imaging (MRI), or other means. However, there is frequently a delay between the positioning of the device and the taking of the biopsy sample, so that the device or tissue may move and prevent acquisition of the desired tissue. Accordingly, there is need in the art for means to mark a target site within a patient""s body and for means to anchor the biopsy device in a proper location.
The tissue to be sampled or removed from the patient will often comprise a volume larger than the volume of the biopsy probe to obtain disease-free margins for pathological diagnosis. Accordingly, means for obtaining tissue samples larger than the probe itself are desired. In addition, it is of clinical interest to determine the extent of a diseased or abnormal portion of the tissue, and it is often desired that a border of normal tissue, surrounding any abnormal tissue present, be removed as well. It is further desired that the tissue to be removed be isolated from the body to prevent migration of diseased or abnormal tissue into other locations of the patient""s body.
Accordingly, there is need in the art for devices and methods for accessing a desired site within a patient""s body without displacing target body tissue, for anchoring devices at a desired site to prevent movement of such devices after arrival at a desired site, for isolating tissue, and for taking biopsy specimens from a patient.
The present invention is directed to systems, devices and methods for accessing target tissue within a patient, for isolating a body of target tissue from its supporting bed, for performing a lumpectomy, for performing a biopsy, and for obtaining biopsy tissue. Accordingly, the present invention provides systems, devices and methods providing access to a desired subcutaneous site for target tissue within a patient""s body and for isolating such target tissue from a supporting tissue bed.
In one embodiment, a device having features of the invention has an elongated shaft having a distal end, a proximal end and a longitudinal axis. An electrosurgical electrode is secured to the distal end of the shaft with a first electrical conductor extending within the shaft having a distal end electrically connected to the electrosurgical electrode and a proximal end configured to be electrically connected to a high frequency electrical power source. An anchoring mechanism is located proximal to the distal end; and a side-cutting mechanism having a cutting element configured to be rotated about the longitudinal axis of the shaft and thereby isolate a body of target tissue.
In another embodiment, the invention is a biopsy device for obtaining target tissue within a patient. In such an embodiment, it has an elongated shaft that has distal and proximal ends and a longitudinal axis; with an electrosurgical electrode secured to the distal end of the shaft. A device of this embodiment also has an electrical conductor extending within the shaft that is electrically connected at opposite ends to the electrosurgical electrode and to an electrical power source. The device also has an anchoring mechanism and a side-cutting mechanism having a cutting element. The cutting element is configured to be rotated about the longitudinal axis of the shaft and so to isolate a body of target tissue.
In yet a further embodiment, the invention is a device for performing a lumpectomy in a patient""s breast. I t has an elongated shaft with an electrosurgical electrode secured to the distal end of the shaft and an electrical conductor extending within the shaft that is electrically connected to the electrosurgical electrode and to an electrical power source. The device of this embodiment has an anchoring mechanism located and a side-cutting mechanism having a cutting element that can be rotated about the longitudinal axis of the shaft to isolate a body of target tissue for removal.
In another embodiment, the invention provides a method for accessing target tissue at a desired site within a patient and isolating a body of target tissue. This method includes the steps of providing a device of the invention, contacting a patient""s body with the device, and supplying high frequency electrical current to the electrical electrode while advancing the device into the patient and through the site of target tissue. The method also includes steps of an anchoring mechanism to penetrate the surface of the target tissue in order to fix the device at the target tissue site. In addition, the method provides for expanding the cutting element of the side-cutting mechanism into the target tissue and rotating the cutting element to cut a body of target tissue.
In a further embodiment, the invention provides methods for performing a biopsy on target tissue at a desired site within a patient, and of performing a lumpectomy on a breast of a patient. The methods include providing a device of the invention, positioning the electrosurgical electrode of the device in contact with the patient""s body, supplying high frequency electrical current to the electrosurgical electrode while advancing at least a portion of the shaft through the site of target tissue, expanding an anchoring mechanism to fix the device at the target tissue site, expanding the cutting element of the side-cutting mechanism, rotating the cutting element to form a body of target tissue, and withdrawing the device with the body of target tissue from the patient.
In one embodiment, the device of the invention has an elongated shaft with an electrosurgical electrode effective to cut through tissue and to provide access to target tissue within a patient""s body. The electrosurgical electrode is configured to be electrically connected to an electrical power source. An anchoring mechanism is provided to engage the target tissue and thereby anchor the device with respect to such target tissue A side-cutting mechanism is configured to cut a body of target tissue so as to isolate the target tissue from its supporting bed.
In one presently preferred embodiment the side-cutting mechanism includes an elongated electrode oriented along the elongated shaft with one end distal to the anchoring mechanism and one end proximal to the anchoring mechanism. In this fashion the elongated electrode can isolate the target tissue. An electrical conductor extends within the elongated shaft of the device to connect to the elongated electrode of the side-cutting mechanism to an electrical power source. Preferably, a single electrical power source powers both the electrosurgical electrode and the elongated electrode of the side-cutting mechanism although the current frequency and power requirements may be different for the two electrodes.
The anchoring mechanism is an elongated member or preferably a plurality of elongated members such as wires or ribbons which can be advanced generally radially away from the elongated shaft into the body of target tissue to fix the location of the device with respect to the target tissue. The elongated members should be curved outwardly to engage the surface of the target tissue. To facilitate entry of the elongated members into the body of target tissue, in a preferred embodiment the tips are sharp. In other embodiments, the elongated members may be formed of electrically conductive material and high frequency electrical current may be applied to the elongated members. Facilitating entry of the elongated members into tissue eliminates the tenting effects which may occur when the tip of an elongated member contacts the surface of the target tissue and applies pressure thereto. The elongated members of the anchoring mechanism preferably should be movably mounted to the elongated shaft, so that they may be in a retracted configuration when the device is advanced through the patient""s tissue or when the device is rotated to cut and isolate a body of target tissue, and may be extended generally radially to an expanded configuration to engage the target tissue as desired, before cutting and isolation of a body of target tissue and after such cutting and isolation.
The electrical power source is preferably a high frequency, e.g. a radio a frequency (RF), electrical power source. The frequency of the current directed to the elongated electrode of the side-cutting mechanism may be, and is preferably greater than the frequency of the current directed to the electrosurgical electrode on the distal end of the elongated shaft and the elongated members of the anchoring mechanism. For obtaining a biopsy from soft tissue such a breast tissue the electrical energy is provided in a frequency range of about 0.1 MHz to about 10 MHz. In one presently preferred embodiment, the electrical energy is provided to the electrosurgical electrode or the anchoring mechanism, or both, in a frequency range of about 0.3 to about 1.5 MHz, preferably about 0.8 MHz. In another presently preferred embodiment, the electrical energy is provided to the elongated electrode of the side-cutting mechanism in a frequency range of about 0.5 to about 10 MHz, preferably about 2.5 to about 7.5 MHz, typically about 5 MHz.
A biopsy entails removal of diseased tissue, as in a lumpectomy. A biopsy may be performed using the device of the invention by directing high frequency electrical current to the electrosurgical electrode on the distal end of the device while pressing the electrosurgical electrode of the device into the patient""s tissue. The electrosurgical electrode and the distal end of the device to which it is secured readily passes through the tissue, making a cut therethrough with little or no heat affected zone at the cut surfaces of the tissue through which the device passes. The distal end of the device may be guided through the patient""s tissue by an imaging system such as an ultrasonic or x-ray imaging system until the anchoring and side-cutting mechanisms are at a desired location within the target tissue. The elongated members of the preferred anchoring mechanism are then advanced out of their contracted configuration so that the distal ends thereof penetrate into the target tissue. The passage of the distal ends of the elongated members is greatly facilitated by directing high frequency electrical current through the members. The anchoring elements of the anchoring mechanism in their expanded configuration fix the device with respect to the target tissue.
The device is now ready to cut a body of tissue from the desired location. To do this, the elongated electrode of the side-cutting mechanism, preferably an arcuate electrode, is expanded outwardly while directing high frequency electrical current through the electrode making a longitudinal radial cut through the target tissue. In a preferred embodiment, the elements of the anchoring mechanism are then retracted, that is, replaced within or along the elongated shaft so that they are no longer in their deployed configuration, after the side-cutting electrode is deployed but before the side-cutting has begun cutting the margins of the tissue to be removed. At this point, preferably with the anchoring mechanism retracted, the expanded side-cutting electrode is then rotated about the longitudinal axis of the device while high frequency current is supplied thereto to separate and isolate a body of target tissue. In a preferred embodiment, the expanded side-cutting electrode rotates completely around the longitudinal axis of the device. In a most preferred embodiment, the expanded side-cutting electrode rotates more than 360xc2x0, preferably 360xc2x0 plus about an additional 45xc2x0, thus insuring that a body of target tissue is entirely isolated from its supporting bed of body tissue, and that the final position of the side-cutting electrode is not directly over the slot created in the tissue as the side-cutting electrode expands outwardly during deployment.
The resulting separated and isolated body of target tissue is substantially in the shape of a spheroid, where a spheroid is a rounded shape generated by revolving a shape around an axis. By substantially in the shape of a spheroid is meant that the shape approximates a spheroid, and so is, e.g., roughly spherical, or elliptical, but may have an irregular shape that only generally approximates a spheroid. For example, the shape of the isolated body of tissue may be roughly cylindrical or conical.
The side-cutting electrode is thus effective to cut and isolate a body of tissue. Following separation and isolation of the a body of target tissue, the elements of the anchoring mechanism may be redeployed, and the device may then be removed from the body of the patient along with the isolated body of target tissue fixed by the anchoring members. In preferred embodiments, the side-cutting electrode, without being supplied with RF power, is partly retracted to aid in anchoring the isolated body of target tissue. A specimen substantially in the shape of a spheroid, such as, e.g., a rounded, substantially spherical or elliptical specimen, containing target tissue isolated by an arcuately shaped electrode greatly simplifies the pathological examination of the specimen both at its center and margins.
For removal of diseased tissue such as breast cancer, the size of the body of target tissue to be removed is usually selected to be significantly larger than the diseased tissue to ensure than all of the diseased tissue is removed. Where an isolated body of target tissue is found to have healthy tissue surrounding more centrally-located diseased tissue, a pathologist may more easily determine whether or not it is likely that any diseased tissue remains in the patient""s body.
An advantage of the present invention is that it provides a roughly spherical specimen of target tissue. A roughly spherical specimen is easily examined to detect the presence and extent of diseased tissue. If the tissue within the specimen is found to be in fact diseased, e.g. to contain a carcinoma, then the entire surface of the roughly spherical specimen should be examined to be sure that there is no diseased tissue at the specimen margins. If the margins are free of diseased tissue, then the physician can be reasonably assured that all of the diseased tissue has been removed. Alternatively, the presence of diseased tissue at the margins of the specimen suggests that additional diseased tissue may remain within the patient""s body.
After removing the target tissue samples or diseased tissues, additional procedures may be performed at the biopsy site or site of diseased tissue. For example, it may be desirable to cauterize, coagulate or otherwise treat the resulting cavity to stop bleeding and reduce the risk of infection or other complications. Where tissue isolation is performed, electrosurgical coagulation may be performed before or after removing the tissue specimen from the patient. Also, it may be advantageous to mark the site for future surgical procedures should pathological tests performed on the biopsy specimen indicate surgical removal or other treatment of the suspected tissue mass from which the specimen was removed. Such marking can be performed, for example, by the apparatus and method disclosed and claimed in co-pending U.S. patent application Ser. No. 09/343,975, filed Jun. 30, 1999, entitled xe2x80x9cBiopsy Site Marker and Process and Apparatus for Applying It,xe2x80x9d which is hereby incorporated by reference in its entirety.
The devices and methods of the invention provide the advantage of anchoring the device at a target location, avoiding movement after a site of interest has been identified within the body of a patient. A further advantage is provided by the ability of the device to cut a body of tissue from that correct location, without needing to position a separate instrument at the site. In addition, the present invention provides a roughly spherical specimen of target tissue, which by its shape is easily examined to detect the presence and extent of diseased tissue.